1. Technical Field
The present invention relates to an electrostatic charge image developing toner used in the electrophotographic image formation, and a method for manufacturing the same.
2. Description of Related Art
Conventionally, in an electrophotographic image forming method that forms visible image by an electrophotographic method, as a method for fixing toner image formed on a transfer medium such as a paper by an electrostatic charge image developing toner (hereinafter also simply referred to as a “toner”), a heat roller fixing system that fixes a transfer medium on which a toner image is formed, by passing between a heating roller and a pressing roller, is widely used. In order to secure fixability in this heat roller fixing system, namely, adhesion of toner on a transfer medium such as a paper, the heating roller requires high heat capacity.
However, recently, from the viewpoint of warming prevention measures of global environment, also to an electrophotographic image forming apparatus, request for energy saving is increased, thus, particularly in the electrophotographic image forming apparatus adopting a heat roller fixing system, many studies have been made for a technology for reducing a calorie required to fixation of a toner image, namely, low temperature fixing of toner, and the representative study includes those using a crystalline material.
For example, a technology that, in a toner containing a crystalline polyester resin and an amorphous resin, the crystalline polyester resin constituting toner base particles as fibrous crystal structures is contained, and the domain diameter is adjusted to promote further sharp meltability, and achieve sufficient low temperature fixability, is suggested (refer to JP 2013-257415 A). Also, a technology that a crystalline polyester resin is finely dispersed with an average diameter of 300 nm or less of a domain phase in a core part of toner particles with a three-layer structure is also suggested to make the crystalline polyester resin exist as a domain phase inside the core, to improve compatibility during thermal fixing, to further reduce the degree of crystallization, and consequently, variation in the degree of crystallinity is reduced, and high gloss uniformity is obtained in the obtained image (refer to JP 2014-186194 A). Furthermore, a technology to define the maximum domain diameter of the crystalline polyester resin present in the core part of toner, thereby suppressing filming while securing excellent low temperature fixability, is also suggested (refer to JP 2009-229920 A).